The advent of solid state power drivers, specifically half-bridge drivers, and their use in power delivery circuits has created the need to monitor and to protect these drivers against prolonged high current conditions due to short circuits. The protection schemes employed heretofore in these power delivery circuits have been complicated, not completely effective and relatively expensive. The conventional circuits utilized hardware protection schemes that included various types of active electrical component circuits such as transistors and other types of switches including current sensing switches. Most often the conventional short circuit protection schemes only provided protection against one type of short, typically, shorts to the power supply's ground.
These power delivery circuits are commonly provided with multiple microprocessor controlled current flow paths. The automobile industry has made use of these multi-current path circuits for controlling motorized automobile devices, such as motorized mirrors. The current flow paths are typically paired to provide current flow control to opposite sides of each motor and therefore control the action of these motors. The motors in these motorized mirror applications are some times additionally equipped with a second control device such as a manual override controller connected in parallel with the microprocessor controlled power delivery circuit. In these applications, the potential exists for the two controllers to compete with each other exposing the power delivery circuit to contention currents resulting from shorts to source power or ground through the second control device.
The ever increasing use of microprocessors to control the current flow in these power deliver circuits provides a ready source of intelligence for use in short circuit protection. The present invention provides short circuit protection in power delivery circuits using a simple passive component electric circuit and a microprocessor.
It is an object of this present invention to provide a power delivery circuit with short circuit protection using a simple passive electrical component circuit and a microprocessor.
It is another object of this present invention to provide a power delivery circuit having short circuit protection against both shorts to source power and to ground.
It is still another object of this present invention to provide a power delivery circuit with short circuit protection responsive to the voltage at the circuit's load connection terminal.
It is yet another object of this present invention to provide a power delivery circuit with short circuit monitoring and protection at each of the circuit's load connection terminals.
It is a further object of the present invention to provide a microprocessor controlled power delivery circuit having short circuit protection that uses simple passive electrical components and the microprocessor.
It is still a further object of the present invention to provide a power delivery circuit having intelligent short circuit protection.
It is yet a further object of the present invention to provide a power delivery circuit having fast-acting hardware short circuit protection coupled with intelligent software short circuit protection.
These and other objects of the present invention will become readily apparent after studying and understanding the present invention, as hereinafter described.